1. Field of the Invention
The present invention relates to an automatic wiring connection apparatus, which is addressed as a main distribution frame (MDF), for determining a connection relation between a cable of telephone subscribers and a cable of telephone exchanges.
2. Description of the Related Art
Hitherto, the above-mentioned automatic wiring connection apparatus is widely used. In such a type of automatic wiring connection apparatus, there is adopted the following scheme of one.
FIG. 1 is a diagram useful for understanding a functional effect of an automatic wiring connection apparatus. FIG. 2 is a typical illustration showing part of wirings and crosspoint holes on a matrix board. FIG. 3 is a sectional view of a connection pin in the state that it has been inserted into a crosspoint hole.
The automatic wiring connection apparatus has a so-called matrix board (MTB). On the front side and the back side of the matrix board, there are formed wirings 11 (in FIG. 2, there is shown part of wirings in the horizontal direction) in the vertical direction and the horizontal direction. And on each of the intersections of the wirings in the vertical direction and the horizontal direction, there is formed a crosspoint hole 12. A land 13 going to the wiring 11 is formed on the periphery of each of the crosspoint holes 12.
In this automatic wiring connection apparatus, the adjacent two wires pair, and a connection pin 14 shown in FIG. 3 is inserted into two crosspoint holes 12 which are adjacent to each other at a slant, so that a connection relation between the wiring in the vertical direction and the wiring in the horizontal direction is determined. In this manner, as shown in FIG. 1, for example, a cable of a subscriber C is connected to the third cable of a telephone exchange. When an application of a new subscriber arises, a connection pin is inserted into the associated crosspoint hole. When applications of a seceder or a remover to another area arise, a connection pin is pull out from the associated crosspoint hole. According to this automatic wiring connection apparatus, an access to crosspoint holes of the matrix board in insertion and pulling out of the connection pin is automatically performed in accordance with an external instruction.
There is known a matrix board having crosspoint holes each being about 0.5 mm across in which many such crosspoint holes are arranged at intervals of about 1.6 mm, as shown in FIG. 2. There is a need to surely insert a connection pin into a desired crosspoint hole, or to properly pull out the connection pin from the crosspoint hole.
In order to insert and pull out the connection pin, a robot mechanism is adopted. In this case, there is a need to provide a precise positioning to properly access to the desired crosspoint hole. The earlier technology copes with the precise positioning by means of enhancing a precision and a rigidity of the robot. However, recently, in view of the requirement of miniaturization and low cost for the robot mechanism, there is a tendency that the robot mechanism is lowered in a precision and a rigidity. Further, the matrix board is also associated with unevenness through manufacturing. Thus, the crosspoint holes are not always located at the position as designed, and rather usually involved in positional deviation somewhat. In addition, recently, as mentioned above, diameters of the crosspoint holes and intervals of the crosspoint holes are fined. Thus, even if only the robot mechanism is enhanced in precision, it is difficult to expect a precise positioning.
For the reasons as mentioned above, according to the earlier technology, a swell and driving errors of a robot, including positional deviation of crosspoint holes on the matrix board, are manually measured on an off-line at the time of manufacturing so as to obtain data, and the data thus obtained are used in the form of a correction function thereby contributing to an improvement in precision of the final positioning of the robot.
However, according to the scheme as mentioned above, workers are needed. This causes the cost to increase. Further, after the apparatus is installed, it is impossible to alter the data. Thus, it is difficult to readily cope with the change in the state of assembly due to the secular change and the disturbance such as an earthquake.
In order to solve the foregoing inconvenience, there has been proposed the use of a 4-division sensor for detecting positions of crosspoint holes on the matrix board (Japanese Patent Application Laid Open Gazette Hei.3-50608).
FIG. 4 is a typical illustration of a 4-division sensor.
A 4-division sensor 20 has four divided sensor areas 21, 22, 23 and 24 and is able to independently detect light volumes V.sub.a, V.sub.b, V.sub.c and V.sub.d which are incident upon the sensor areas 21, 22, 23 and 24, respectively. Positioning is made at the point in which anyone of a difference between light volumes (V.sub.b +V.sub.c)-(V.sub.a +V.sub.d) in a Y-direction and a difference between light volumes (V.sub.c +V.sub.d)-(V.sub.a +V.sub.b) in a Z-direction becomes zero.
FIG. 5 is a typical illustration of errors in perforation position of crosspoint holes.
In the event that a crosspoint hole is detected by the 4-division sensor, there is provided such a control that the crosspoint hole is irradiated with light and the 4-division sensor is translated toward a position in which light volume of the reflected light from the crosspoint hole balances in both the Y-direction and the Z-direction. Exactly, the crosspoint hole per se is an opening and thus no reflected light from the crosspoint hole exists. Accordingly, actually, the reflected light from the land of the vicinities of the crosspoint hole is detected. However, generally, a formation of the wires and the lands, and a perforation of the crosspoint holes are different from one another in a manufacturing process. Thus, a positional relation between the crosspoint hole and the land is not always a positional relation as designed, such as a positional relation between the crosspoint hole 12a and the land 13a shown in FIG. 5, and it happens that as in the crosspoint hole 12b of the center of FIG. 5 the crosspoint hole is located near the corner of the land 13b, or alternatively it happens that as in the crosspoint hole 12c of the right of FIG. 5 the crosspoint hole is partially out of the land 13c. In those cases, the light volume does not balance properly in the use of the 4-division sensor. Thus, it is impossible to expect a proper detection.
On the other hand, when it is intended that a matrix board, which is proper in a positional relation between a crosspoint hole and a land, is produced, this would involve a big raise in cost. It may be considered that even if a position of a crosspoint hole is deviated, an area of a land is extended so that the crosspoint hole is always accommodated in the land. In this case, however, there is a need to expand a pitch between crosspoint holes and a wiring interval. Thus, this is contrary to a requirement of miniaturization of the apparatus.
Further, there is a proposal (Japanese Patent Application Laid Open Gazette Hei.1-260994) that a hole as a position detection mark is provided in association with the respective crosspoint hole, but a crosspoint hole is not directly detected. In the event that marks (holes) are provided other than the crosspoint holes, it is possible to provide a mark (hole) suitable for a sensor, and thus it is advantageous for a positional detection. However, this involves a need to provide a pair of the position detection mark and the crosspoint hole, and thus it is difficult to enhance an integration degree of crosspoint holes on a matrix board.